Safety device fob hot-wateb systems



Dec. 1; 1925.

G. A. ROBERTSHAW SAFETY DEVICE FOR HOT WATER SYSTEMS Filed June 2'7,1923 2 Sheets-Sheet 1 G. A. ROBERTSHAW SAFETY DEVICE FOR HOT WATERSYSTEMS Dec.- 1 I 1925. 1,564,115

Filed June 27, 192,3 2 Sheets-Sheet 2 Patented Dec. 1, 1925.

UNITED STATES.

A 1,564,115 PATENT OFFICE.

,, GEORGE A. ROBERTSHAW, 0F GREENBURG, PENNSYLVANIA.

SAFETY DEVICE FOR HOT-WATER SYSTEMS.

Application filed June 27, 1923. Serial No. 648,001f

- a thermostatically operated valve for controlling the supply of gas tothe burner in a hot water system. In such a system the circulating pipeand heating coils fill up most rapidly due to corrosion and depositsbecause these are the parts which are subjected to the highesttemperatures. It is possible to create a dangerous pressure inthecirculating pipe and coils if the circulation is retarded. Therefore,it is desirable to provide means controlled by the temperature of thecirculating pipe for cutting off the supply of gas when that temperatureexceeds the limit of safety. A thermostat inserted in the circulatingpipe is subject to corrosion or insulating deposits and otherdisadvantages. By the present invention there is provided a safetydevice of simple construction and embodying avalve to be placed in thegas supply line and a fuse for controlling the valve and adapted to bepositioned upon the exterior of the circulatlng P In the accompanyingdrawing, there 1s shown, for purposes of illustration only, oneembodiment of-the present invention, it being understood that thedrawings do not define the limits of the invention, as changes may bemade in the construction and operation therein disclosed withoutdeparting from the s irit of the invention or scope of my broa orclaims.

In the drawings:

Figure 1 is a side elevation of a hot water system having a safetydevice in accordance with my invention associated therewith;

Figure 2 is a view partly in section and partly in elevation of thesafety device and assoclated parts of the hot water system;

Fi re 3 is a sectional viewtaken on the line II- III of Figure 2; and

Figure 4. is a perspective view of the fusl ble link.

In Figure 1 there is shown a hot water system of usual construction,comprising a boiler A and a gas heater B. Gas is supplied to the burner2 of the heater through the u'su'alpipe 3. This pipe may have athermostat 4 therein for controlling the supply of gas to the burner 2within normal temperature ranges, or this thermostat may be omitted. Thecirculating pipe is indi.

cated by the reference numeral 5.

The safety device of the present invention may comprise a suitableT-shaped valve casing 6 tapped into the gas supply pipe 3 and having avalve seat 7 with which cooperates a valve 8. The leg 9 of the T-shapedcasing 6 is screw threaded for cooperation with the screw threadedreduced portion 10 of a head 11 which is screwed into said leg until theshoulder 12 between said reduced portion 10 and the head engages the endof said leg thereby forming a gas tight closure. The stem 13 of thevalve 8 extends through an opening 14 in the head 11. The reducedportion 10 is provided with a recess 15 and surrounding the stem 13 andarranged in said7recess is a packing gland 16 and a washer 1 Surroundingthe stem 13 and interposed between the washer 17 and the valve 8 is acoil spring 18. Revolubly mounted upon a reduced portion of the head'lland extending towards the circulating pipe 5 are a pair of legs 19having curved feet 20in engagement with said pipe 5. Thelegs 19constitute means for maintaining the pipes 3 and 5 roperly spaced apartagainst the reaction 0 the 0011 spring 18 in case the gas supply pipe 3is not firmly supported, and as these logs are revolubly mounted, thevalve casing 6 may be placed in a vertical, horizontal or inclinedposition. The stem 13 is provided with one or moreopenings 21 extendingtransversely therethrough. Engaged in one of theopenings 21 is one endof an S shaped hook 22.. The valve 8 is normally maintained away fromits seat 7 by means of a fusible link surrounding the pipe 5 and engaginthe other end of the hook 22. This fusible link is shown in detail inFigure- 4 and may comprise sim 1y a pair of wires 23 each of which isdouhled upon itself to form a loop 24, the free ends of the two doubledwires 23 being joined by a spot of 110 fusible solder 25. The solder tobe employed will be one melting at a temperature below that considereddangerous. Preferably, it will consist of an alloy of lead, tin andbismuth or cadmium. In hot water heaters a melting temperature of 200 to25Q F. 1s generally considered low enough to prevent a dangerously highpressure in the system.

In case the gas supply pipe 3 is firmly supported, it will not benecessary to provide the legs 19 on the head 11. Moreover, when thedevice is used on heaters which do not have a circulating pipe, thefusible link may be attached to the outside of the boiler or to the hotwater outlet pipe near the boiler.

The advantages of the present invention are many. The fusing solder isopen to the atmosphere and is not subject to corrosion or insulatingdeposits. The fusible link may be.replaced without shutting off thewater or otherwise disturbing the system. There is no special tappingrequired in order to associate the safety device with the system. Thefusible link may be located on the circulating pipe, in which dangeroustemperatures and. pressures are most likely to. develop. Thespring-closing valve with internal self-adjusting packing gland is notaccessible from the exterior so that it cannot be tampered with. TheS-hook for engagement with the loops. 24 of the fusible link permits thevalve 8 to be turned 180. The fusible link is inexpensive to manufactureand the same link may be utilized over and over again by simplyreuniting the free ends thereof with the spot of fusible solder. The

entire device is of extremely simple construcother system.

WVhile I have illustrated my invention as applied to a hot water system,it will. be understood that its use is not necessarily limited to suchsystems.

I claim:

1. In a hot water circulating system, the combination with a gas-supplypipe and a hot-water circulating pipe, of a safety device comprising avalve tapped into the gas-supply pipe, means tending to move said valveinto engagement with its seat, and means for normally maintaining saidvalve away from its seat, comprising a fusible link looped. around saidhot-water circulating pipe and connected to said valve, substantially asdescribed. y

2. In a hot water system, the combination with a gas-supply pipe andhot-water circulating pipe, of a safety device comprising a valve tappedinto the gas-supply pipe, means tending to move said valve intoengagement with its seat, means for normally maintaining said valve awayfrom its seat, comprising afusible link looped around said hot-watercirculating pipe and connected to said valve, and spacing means engagingthe valvecasing and said hot water circulating pipe, substantially asdescribed;

In testimony whereof I have hereunto set my hand.

GEORGE A. ROBERTSHAW.

